In marine environments in particular, economic and safety considerations often dictate that larger installations be composed of a number of smaller sub-units linked or preferably hinged together. The hinged joints between sub-units are all severely stressed when differential movement between sub-units occurs due to wave and tidal action, wind, currents, ice and of course normal loading on the sub-units themselves. The installations in question typically include piers, docks, floating platforms and structures assembled and used for the purpose of aquaculture, that is, facilities assembled, anchored and maintained in an exposed marine environment for the holding, raising or culturing of fish stocks and crustaceans. As will be appreciated, such installations are often, if not typically, located in extremely hostile environments, including exposed shorelines and open stretches of water, tidal bays and estuaries and similar habitats. Wind and wave-induced stresses in particular are highly destructive to the extent that many such environments have so far proven completely inhospitable to any installation intended to provide a measure of relative permanence.
For the structures in question to survive, the hinge joints between sub-units must provide a firm coupling, that is, joints with a minimum of play, but at the same time, shock, stress and torsion must be at least partially absorbed without transmission to the structural components of the sub-units.
These characteristics have not so far been successfully combined in an economically and structurally feasible hinge.